LMMSAT - TESDA QA SYSTEM Shielded M etal Arc Welding NC II Date Developed: Document N. Issued by: Developed by: Jerry R. Torrado Revision No.__ Page _ of __ COMPETENCY - BASED LEARNING MATERIALS Sector: METALS AND ENGINEERING ( SECTOR ) Qualification: SHIELDED METAL ARC WELDING NC II Unit of Competency: WELD CARBON STEEL PIPES USING SMAW Module Title: WELDING ON CARBON STEEL PIPES Institution: LMMSAT - TESDA Poblacion West, Asingan, Pangasinan
Transcript
LMMSAT -
TESDA
QA
SYSTEM
Shielded Metal
Arc Welding NC II
Date Developed:
Document N.
Issued by:
Developed by:
Jerry R. Torrado
Revision
No.__
Page _ of __
COMPETENCY - BASED LEARNING MATERIALS
Sector: METALS AND ENGINEERING
( SECTOR )
Qualification:
SHIELDED METAL ARC WELDING NC II Unit of Competency:
HOW TO USE THIS COMPETENCY BASED LEARNING MATERIAL
Welcome to the module in Welding Carbon Steel Pipes Using SMAW. This
module contains training materials and activities for you to complete.
The unit of competency “Weld Carbon Steel Pipes Using SMAW” contains
knowledge, skills and attitudes required for Shielded Metal Arc Welding NC II. It
is one of the specialized modules at National Certificates Level (NC II).
You are required to go through a series of learning activities in order to
complete each learning outcome of the module. In each learning outcome are
Information Sheets and Resources Sheets (Reference Materials for further
reading to help you better understand the required activities). Follow these
activities on your own and answer the self-check at the end of each learning
outcome. You may remove a blank answer sheet at the end of each module (or
get one from your facilitator/trainer) to write your answers for each self-check. If
you have questions, don’t hesitate to ask you facilitator for assistance.
Recognition of Prior Learning (RPL)
You may already have some or most of the knowledge and skills covered in this
learner’s guide because you have:
been working for some time
already completed training in this area
If you can demonstrate to your trainer that you are competent in a particular
skill or skills, talk to him/her about having them formally recognized so you don’t
have to do the same training again. If you have a qualification or Certificate of
Competency from previous trainings, show it to your trainer. If the skills you
acquired are still current and relevant to the unit/s of competency they may
become part of the evidence you can present for RPL. If you are not sure about
the currency of your skills, discuss this with your trainer.
At the end of this module is a Learner’s Diary. Use this diary to record
important dates, jobs undertaken and other workplace events that will assist you
in providing further details to your trainer or assessor. A Record of Achievement
is also provided for your trainer to complete once you complete the module.
This module was prepared to help you achieve competency, in Welding Carbon
Steel Pipes Using SMAW. This will be the source of information for you to
LMMSAT -
TESDA
QA
SYSTEM
Shielded Metal
Arc Welding NC II
Date Developed:
Document N.
Issued by:
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Revision
No.__
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acquire knowledge and skills in this particular trade independently and at your
own pace, with minimum supervision or help from your instructor.
Talk to your trainer and agree on how you will both organize the Training of this unit. Read through the module carefully. It is divided into sections,
which cover all the skills, and knowledge you need to successfully complete
this module.
QUALIFICATION: SHIELDED METAL ARC WELDING NC II
UNIT OF COMPETENCY: Weld Carbon Steel Pipes Using SMAW
MODULE TITLE: Welding Carbon Steel Pipes Using SMAW
INTRODUCTION: This module covers the knowledge, skills and
proper attitude in groove welding on carbon steel
pipes in performing root pass, clean root pass, weld
subsequent/ filling passes, and perform capping.
NOMINAL DURATION: 80 HOURS
LEARNING OUTCOMES:
Upon completion of this module, the trainee/student must be able to: 1. Perform root pass
2. Clean root pass
3. Weld subsequent/filling pass
4. Perform capping
ASSESSMENT CRITERIA:
1. Root pass is performed in accordance with WPS and/or client
specifications.
2. Task is performed in accordance with company or industry requirement
and safety procedure.
3. Weld is visually checked for defects and repaired, as
4. required
5. Weld is visually acceptable in accordance with applicable codes and
standards
6. Root pass is cleaned and free from defects and discontinuities
7. Task is performed in accordance with approved WPS
8. Subsequent/ filling passes is performed in accordance with approved WPS
LMMSAT -
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Shielded Metal
Arc Welding NC II
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9. Weld is visually checked for defects and repaired, as required
10. Weld is visually acceptable in accordance with applicable codes and
standards
11. Capping is performed in accordance with WPS and/or client specifications
12. Weld is visually checked for defects and repaired, as required
13. Weld is visually acceptable in accordance with applicable codes and
standards
PRE-REQUISITE:
BASIC AND COMMON COMPETENCIES
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Shielded Metal
Arc Welding NC II
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LEARNING OUTCOME #1: Perform root pass
Learning Contents: 1. Essentials of welding
2. Safe welding practices 3. Weld defects, causes and remedies
4. Welding Procedure and Specifications (WPS)
5. International welding codes and standards
6. Acceptable weld profiles
7. Welding technique and procedures
ASSESSMENT CRITERIA:
1. Root pass is performed in accordance with WPS and/or client specifications.
2. Task is performed in accordance with company or
industry requirement and safety procedure.
3. Weld is visually checked for defects and repaired, as
required 4. Weld is visually acceptable in accordance with applicable codes
7. Read Information Sheet 1.1 – 4 on Welding Procedures and Specifications
(WPS).
Read the information sheet carefully
8. Answer Self – Check 1.1 -4 (Written Test)
Compare to answer key 1.1-4.
9. Read Information Sheet 1.1-5 on
International welding codes and standards.
Read the information sheet
carefully
10. Answer Self – Check 1.1 -5 (Written
Test)
Compare to answer key 1.1-5.
11. Read Information Sheet 1.1-6 on
acceptable weld profiles.
Read the information sheet
carefully
12. Answer Self – Check 1.1 -6 (Written Test)
Compare to answer key 1.1-6.
13. Guided by information sheet 1.1-7,
observe the trainer as he demonstrates the different welding techniques and
procedures correctly and properly.
Jot down observations.
14. Perform Job Sheets 1.1-7a-c on the different welding techniques and
procedures.
Trainer evaluates performance
and work outputs and makes
recommendations.
LMMSAT -
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Shielded Metal
Arc Welding NC II
Date Developed:
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INFORMATION SHEET No. 1.1-1
ESSENTIALS OF WELDING
After reading the Information Sheet, the trainee must be able to
determine the essentials of welding.
Weld quality and consistency can only be maintained with respect to the five
essentials. The five essentials of welding include the use of correct electrode size, current, arc length or voltage, travel speed and electrode angles. All five must be
collectively and consistently maintain to successfully control the puddle and
produce a weld that is uniform in appearance, have consistent ripples, smooth
face contour, and no noticeable defect. Once the welder masters the ability to consistently maintain the five essentials, the ability to control the puddle will
follow.
ELECTRODE SIZE
Choosing the correct electrode size involves many factors. If a smaller
recommended electrode is used, welding time and heat to the joint will increase. It
can result in increase costs, heat affected zone, cracking or distortion.
Larger electrode can cause melt – through and can be difficult to control in out of position
joints. Poor appearance and possible defects can result. The welding procedure
designates the correct electrode size, generally based on metal type and thickness.
However, if no procedure or instruction is available the welder will have to choose
the correct electrode size.
CURRENT
The correct current setting is vital for maintaining consistency in weld quality. If the current is too high, the electrode melts too fast, and the molten pool
is larger and irregular. If the current is too high when welding single vee-groove, it
might blow holes through the joint and cause large molten metal droplets to fall
out of the groove.
If the current is too low, there is not enough heat to melt the base metal. The molten pool will be too small, piles up, and looks irregular. Poor penetration
and incomplete fusion in the joint can result.
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Shielded Metal
Arc Welding NC II
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TRAVEL SPEED
Incorrect travel is a common mistake. Sometimes travel speed is the only condition a welder may need to change. Travelling too fast causes the puddle to
freeze too quickly. Because of this, impurities and gases can become entrapped,
making the bead face narrow with pointing ripple. Incomplete penetration due to
loss of the keyhole in root pass is possible. Travelling too slow will cause the puddle to be large, with pile – up, and a
straight ripple pattern. For out of position welding, slow travel sped can cause the
puddle to drip out the joint.
ELECTRODE ANGLE One of the most essentials is the use of the correct electrode angles. For
fillet and groove welds, correct electrode angles are vital for preventing undercut
and inadequate fill. When depositing a fillet weld the electrode should be held so
that it bisects the angle between the plates and is perpendicular to the line of the
weld. On groove weld, the technique is much the same; although varying slightly with multiple pass welding.
There are two teams to specify electrode angles. These are travel angle and
work angles.
The travel angle applies to the position the electrode make with a reference perpendicular to the axis of the weld in plane of the weld axis. It can be either a
drag angle or a push angle. A drag angle is when the electrode is pointing
backward, meaning the welder’s hand and electrode holder proceeds the puddle. A
push angle is when electrode is pointing just the opposite of the drag.
The work angle is the position the electrode makes with reference to the surface of the plate on a plane perpendicular to the weld axis. On butt joints the
work angle is usually 90 degrees to the surface of the plate.
T o some degree, you can correct for an improper condition by varying the
essential variables. It is better though to have all conditions as correct as possible.
ARC LENGTH
Arc length is very important for weld puddle control. Correct arc length will
cause the deposit to be neat of even ripple and of good penetration. Too long arc length will cause the deposit to coarse rippled and flatter than
normal with an increase in spatter. When welding a root pass in an open root vee
groove, the keyhole can grow too large and loose of weld control can result.
Too short an arc will cause deposited to be narrow, uneven and irregular
rippled and with poor fusion. The arc length reduces the voltage and increases the
amperage slightly but the electrode may stick to the work. When welding root
passes, too short an arc length often results n loss of the keyhole.
LMMSAT -
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Shielded Metal
Arc Welding NC II
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SELF – CHECK 1.1-1
(Essentials of Welding)
TRUE OR FALSE
Direction: Read each statement below carefully. Write TRUE if the statement is
correct and FALSE if the statement is not correct.
______ 1. Using a larger electrode diameter can cause melt – through/ burn –
through.
______ 2. Travelling too fast will make the bead face narrow with pointing ripple.
______ 3. If the current is too low, the electrode melts too fast.
______ 4. Quality or sound weld is the result of correct current, constant voltage,
travel speed, electrode angle and correct electrode size.
______ 5. In fillet weld, electrode angle is not necessary for preventing undercut
and under fill.
LMMSAT -
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Shielded Metal
Arc Welding NC II
Date Developed:
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ANSWER KEY 1.1 – 1
Essentials of Welding
1. TRUE
2. TRUE
3. FALSE
4. TRUE
5. FALSE
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Shielded Metal
Arc Welding NC II
Date Developed:
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INFORMATION SHEET NO. 1.1 -2
Welding Personal Protective Equipment (PPE)
After reading the Information Sheet, the trainee must be able to identify the
different personal protective equipment and their uses.
The hazards in arc welding can endanger a welder’s life if he/she is not wearing the proper protective clothing and equipment. Here are some information
on the suitable outfit that a welder must wear while welding:
WELDING SHIELD/HELMET
Welding shield/helmet is used to protect the face and eyes from the arc rays
(Infrared Rays, Ultra Violet Rays) and heat and spatter from the molten metal. The
arc is viewed through a filter which reduces the intensity of radiation but allows a
safe amount of light to pass for viewing the weld pool and end of the electrode. The recommended minimum protective filter based on the welding current to
be used is shown in the table below:
Approximate Range Of Welding Current Filter Lens Number
Up to 100
100 - 200 200 - 300
300 - 400
Over 400
8
10 11
12
13
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Shielded Metal
Arc Welding NC II
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LEATHER JACKET
Leather jacket is made of chrome leather and prevents the entry of sparks between the welder’s clothes and body.
LEATHER APRON
Leather apron is made of chrome leather and provides a welder with
complete protection from sparks and hot metal from his/her chest to mid calf.
LMMSAT -
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Shielded Metal
Arc Welding NC II
Date Developed:
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LEATHER GLOVES
Gloves are made of chrome leather and protect the welder’s hands from heat, spatter, and radiation.
LEATHER SPATS
Spats are made of chrome leather and protect the feet from spatter.
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Shielded Metal
Arc Welding NC II
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SAFETY GLASSES
Safety clear glasses are used to protect the eyes when chipping slag and grinding.
WELDERS CAP
Welders cap is used to protect welder’s head from spatters in out of
position welding or in confined spaces.
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Shielded Metal
Arc Welding NC II
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WELDERS LEATHER BOOTS
Welding Leather Boots is used to protect our feet from falling spatter, sparks, and hot metals when welding overhead and confined spaces.
FACE SHIELD
Face Shield must also be worn where required to protect eyes. Welders must
wear safety glasses and chippers and grinders often use face shield in addition to safety glasses.
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Shielded Metal
Arc Welding NC II
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SELF – CHECK 1.1-2
Welding Personal Protective Equipment (PPE)
MULTIPLE CHOICE: Choose the correct answer and write the letter that
correspond to your choice on the answer sheet provided.
1. A safety gadget used to protect the face and eyes from the arc rays, heat and spatter.
a. Welding gloves
b. Welding jacket
c. Safety shoes
d. Welding helmet/shield
2. The most serious danger from exposure to welding arc is,
a. X – rays
b. Beta – rays c. Ultra Violet Rays
d. Sun rays
3. Protect the entry of falling hot slag and spatter.
a. Leggings b. Welding gloves
c. Welding helmet
d. Clear glass
4. When welding at a current setting of 120 amperes, what is the recommended
filter lens number?
a. 8
b. 12
c. 10 d. 11
5. Safety gadget used to protect the eyes when chipping slag and grinding.
a. Safety glasses b. Leather spats
c. Leggings
d. Welding gloves
LMMSAT -
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Shielded Metal
Arc Welding NC II
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ANSWER KEY 1.1 – 2
Welding Personal Protective Equipment (PPE)
1. d
2. c
3. a
4. c
5. a
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Shielded Metal
Arc Welding NC II
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INFORMATION SHEET 1.1 -3
Identifying Weld Defects, Causes and Remedies
After reading the Information Sheet, the trainee must be able to:
1. Identify the different welding defects and causes; and
2. Know the causes and remedies for these defects.
As previously explained, weld quality can only be attained by following the
five essentials, as preconditions for welding. Without due regard to these
essentials, defects will occur. The most common defects and corresponding causes
and preventions are discussed below.
A. POROSITY
CAUSES:
1. Short arc with exception of low hydrogen
2. Insufficient paddling 3. Impaired base metal
4. Poor Electrode
5. Improper Shield Coverage
REMEDIES:
1. Check Impurities in base metal
2. Allow sufficient paddling
3. Use proper current
B.POOR PENETRATION
CAUSES:
1. Speed too fast 2. Electrode too large
3. Current too low
4. Faulty penetration
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Shielded Metal
Arc Welding NC II
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REMEDIES:
1. Use enough current to obtain desired penetration- weld slowly
2. Select electrodes according to welding groove size
3. Leave proper gap at bottom of weld
C.WARPING
CAUSES:
1. Shrinkage of weld metal
2. Faulty clamping of parts
3. Faulty preparation
4. Over heating at joint
REMEDIES:
1. Peen joint edges before welding
2. Weld more rapidly 3. Avoid excessive space between parts
4. Pre-form parts before welding
5. Use proper sequence
6. Clamp or tack parts properly – back up to cool 7. Adopt a proper welding procedure
8. Use high speed, moderate penetration process
D.UNDERCUTING
CAUSES:
1. Faulty Electrode or poor manipulation
2. Faulty Electrode use 3. Correct to high
REMEDIES;
1. Use a uniform weave in butt welding
2. Avoid using an overly large electrode 3. Avoid excessive weaving
4. Use moderate current weld slowly
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Shielded Metal
Arc Welding NC II
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E. CRACK WELDS
CAUSES:
1. Wrong electrode
2. Weld and parts sizes unbalanced 3. Faulty welds
4. Faulty preparation
5. Rigid joint
REMEDIES:
1. Design structure to eliminate rigid joints
2 Heat parts before welding
3. Avoid welds in string beads 4. Keep ends free to move as long as possible
5. Make sound welds of good fusion
6 Adjust weld size to parts size
7. Allow joints a proper and uniform gap
8 Work with amperage as low as possible
F.POOR APPEARANCE
CAUSES:
1. Faulty electrode
2. over hang
3. Improper use of electrode
4. Wrong arc voltage and current
REMEDIES:
1. Use a proper welding technique
2. Avoid over heating
3. Use a uniform weave 4. Avoid overly high current
LMMSAT -
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Shielded Metal
Arc Welding NC II
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G.POOR FUSION
Lack of fusion, also called cold lapping or cold shuts
CAUSES:
1. Wrong speed
2. Current improperly adjusted 3. Faulty preparation
4. Improper electrode size
REMEDIES:
1. Adjust electrode to match joint 2. Weave must be sufficient to melt sides of joint
3. Select proper current and voltage
4. Keep weld metal from flowing away from plates
H. SPATTER
CAUSES:
1. Arc blow
2. Current too high
3. Arc too long 4. Faulty electrode
REMEDIES:
1. Clean parts in weld area
2. Adjust current
3. Adjust voltage 4. Pick suitable electrode
LMMSAT -
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Shielded Metal
Arc Welding NC II
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SELF – CHECK 1.1-3
Identifying Weld Defects, Causes and Remedies
MULTIPLE CHOICE: Choose the correct answer and write the letter that
correspond to your choice on the answer sheet provided.
1. When electrode coating absorbs moisture, what will be the effect to the weld
bead?
a. poor penetration
b. porosities
c. excessive penetration d. undercut
2. Incomplete sidewall fusion is normally found between
a. weld and base metal b. HAZ and base metal
c. root joint
d. cover pass and filling pass
3. Welding distortion, warp and stresses are cause by a. weaving technique
b. intermittent welding
c. high temperature heat
d. backstop welding
4. The most common cause of undercut in a weld is too
a. low a current
b. high an arc
c. short an arc d. high a current
5. Which of the following weld defects DOES NOT have any tolerance for
acceptance? a. crack
b. porosity
c. slag inclusion
d. undercut
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Shielded Metal
Arc Welding NC II
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ANSWER KEY 1.1 –3
Identifying Weld Defects, Causes and Remedies
1. b
2. a
3. c
4. d
5. a
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Shielded Metal
Arc Welding NC II
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INFORMATION SHEET 1.1 -4
Welding Procedure Specification (WPS)
After reading the Information Sheet, the trainee must be able to:
1. Identify welding procedure specification:
2. Interpret welding procedures specification.
A Welding Procedure Specification (WPS) is a formal document describing welding procedures. The purpose of the document is to guide welders to the
accepted procedures so that repeatable and trusted welding techniques are used.
A WPS is developed for each material alloy and for each welding type used. Specific
codes and/or engineering societies are often the driving force behind the development of a company's WPS. A WPS is supported by a Procedure
Qualification Record (PQR or WPQR). A PQR is a record of a test weld performed
and tested (more rigorously) to ensure that the procedure will produce a good
weld. Individual welders are certified with a qualification test documented in a
Welder Qualification Test Record (WQTR) that shows they have the understanding and demonstrated ability to work within the specified WPS.
The following are definitions for WPS and PQR found in various codes and
standards:
According to the American Welding Society (AWS), a WPS provides in detail
the required welding variables for specific application to assure repeatability by
properly trained welders. The AWS defines welding PQR as a record of welding variables used to produce an acceptable test weldment and the results of tests
conducted on the weldment to qualify a Welding Procedure Specification.
The American Society of Mechanical Engineers (ASME) similarly defines a WPS as a written document that provides direction to the welder or welding
operator for making production welds in accordance with Code requirements.
ASME also defines welding PQR as a record of variables recorded during the
welding of the test coupon. The record also contains the test results of the tested
specimens.
In Europe, the European Committee for Standardization (CEN) has adopted
the ISO standards on welding procedure qualification (ISO 15607 to ISO 15614)
and on welder qualification (ISO 9606), with the exception of qualification for steel welders, where a new version of the old European EN 287-1 standard still applies.
EN ISO 15706 defines a WPS as "A document that has been qualified by one of the
methods described in clause 6 and provides the required variables of the welding
procedure to ensure repeatability during production welding". The same standard
defines a Welding Procedure Qualification Record (WPQR) as "Record
comprising all necessary data needed for qualification of a preliminary welding
procedure specification ".In addition to the standard WPS qualification procedure specified in ISO 15614, the ISO 156xx series of standards provides also for
alternative WPS approval methods. These include: Tested welding consumables
(ISO 15610), Previous welding experience (ISO 15611), Standard welding
procedure (ISO 15612) and Preproduction welding test (ISO 15613).
In the oil and gas pipeline sector, the American Petroleum Institute API 1104
standard is used almost exclusively worldwide. API 1104 accepts the definitions of
the American Welding Society code AWS A3.
Welding Procedure Specification:- (Example FORM)
Weld Procedure Number 30 P1 TIG 01 Issue A
Qualifying Welding Procedure (WPAR) WP T17/A
Manufacturer: National Fabs Ltd
25 Lane End
Birkenshaw
Leeds
Location: Workshop
Welding
Process: Manual TIG
Joint Type: Single Sided Butt Weld
Method Of
Preparation
and Cleaning:
Machine and Degrease
Parent Metal Specification:
Grade 304L Stainless Steel
Parent Metal
Thickness 3 to 8mm Wall
Pipe Outside
Diameter 25 to 100mm
Welding Position: All Positions
Welding
Progression: Upwards
Joint Design Welding Sequences
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Arc Welding NC II
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Run Process
Size Of
Filler
Metal
Current
A
Voltage
V
Type Of
Current/Polarity
Wire
Feed
Speed
Travel
Speed
Heat
Input
1
2 And
Subs
TIG
TIG
1.2mm
1.6mm
70 - 90
80 -
140
N/A DC-
DC- N/A N/A N/A
Welding Consumables:-
Type, Designation Trade Name:
Any Special Baking or Drying: Gas Flux:
Gas Flow Rate - Shield:
- Backing:
Tungsten Electrode Type/ Size: Details of Back Gouging/Backing:
Preheat Temperature:
Interpass temperature:
Post Weld Heat Treatment
Time, temperature, method: Heating and Cooling Rates*:
BS 2901 Part 2 : 308S92
No Argon 99.99% Purity
8 - 12 LPM
5 LPM
2% Thoriated 2.4mm Dia. Gas Backing
5°C Min
200°C Max
Not Required
Production
Sequence
1. Clean weld
and 25mm
borders to
bright metal using
approved
solvent.
2. Position
items to be welded
ensuring
good fit up
and apply
purge
3. Tack weld
parts
together
using TIG, tacks to at
least 5mm
min length
4. Deposit root
run using 1.2mm dia.
wire.
5. Inspect root
run internally
6. Complete
weld using
1.6mm dia.
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Shielded Metal
Arc Welding NC II
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wire using
stringer
beads as required.
7. 100% Visual
inspection of
completed weld
LMMSAT -
TESDA
QA
SYSTEM
Shielded Metal
Arc Welding NC II
Date Developed:
Document N.
Issued by:
Developed by:
Jerry R. Torrado
Revision
No.__
Page _ of __
SELF – CHECK 1.1 – 4
Welding Procedure Specification (WPS)
Test I – IDENTIFY THE FOLLOWING:
1. ASME
2. AWS
3. API 1104
4. ISO 15612
5. ISO 15613
Test II – ESSAY (5pts.)
1. What is WPS?
LMMSAT -
TESDA
QA
SYSTEM
Shielded Metal
Arc Welding NC II
Date Developed:
Document N.
Issued by:
Developed by:
Jerry R. Torrado
Revision
No.__
Page _ of __
ANSWER KEY 1.1 -4
Welding Procedure Specifications
Test I:
1. Welding Procedure Specification
2. American Welding Society
3. American Petroleum Institute 1104 - oil and gas pipeline sector
4. Tested welding consumables
5. Standard welding procedure
Test II
1. A Welding Procedure Specification (WPS) is a formal document describing
welding procedures. The purpose of the document is to guide welders to the
accepted procedures so that repeatable and trusted welding techniques are used.
1) base metal – the metal that is to be worked or welded
2)weld bead – a deposit of filler metal from a single welding pass 3)weld defect– an irregularity that spoils the weld appearance or
impairs the effectiveness of the weld or weldment by
causing weakness or failure
4) weld line – the junction of weld metal and the base metal, or
the junction of base metal parts when filler metal is not used 5) weldment – an assembly or structure whose component parts are joined
by welding
6) welding – joining two metals by applying heat to melt and fuse
them, with or without filler metal
7) welding electrode – the current-carrying rod used to strike an arc between rod and metal
8) welding rod – filler metal in the form of a rod or heavy wire
9) welding torch –a gas mixing and burning tool for the welding of metal
10) undercut – is a groove at the toe ( or at the root) of a weld run due on welding. 11) slag inclusion – these are caused by slag trapped in the weld metal.
12) incomplete penetration – failure of weldment to extend into the root of the
joint
to provide full throat depth.
13) porosity – is entrapped gas cavities formed during solidification of the weld 14) cracks – are fractured that displace an opening or a split in the weld or
base metal.
15) Codes – documents that govern and guide welding and other activities.
Codes generally use the word shall to indicate the mandatory use of certain types of materials, methods and procedures.
16) Standards – Documents that govern and guide welding and other
activities. Standards generally describe the requirements for
materials, process, products, systems or services rendered.
17) Specifications – Are similar to codes excepts that specifications mainly provide requirements for products rather than processes.
18) Welding Procedure Specification (WPS) - is a formal document
describing welding procedures. The purpose of the document is to
guide welders to the accepted procedures so that repeatable
and trusted welding techniques are used. 19) welding helmet – is used to protect the face and eyes from the arc rays, heat
and
spatter.
20) welding gloves – are made of chrome leather to protect welder’s hands from heat
